Addressing a Github issue

Author: normesta

articles/storage/common/storage-use-azcopy-s3.md

@@ -41,8 +41,10 @@ Gather your AWS access key and secret access key, and then set these environment
 | Operating system | Command  |
 |--------|-----------|
 | **Windows** | `set AWS_ACCESS_KEY_ID=<access-key>`<br>`set AWS_SECRET_ACCESS_KEY=<secret-access-key>` |
-| **Linux** | `export AWS_ACCESS_KEY_ID=<access-key>`<br>`export AWS_SECRET_ACCESS_KEY=<secret-access-key>` |
-| **macOS** | `export AWS_ACCESS_KEY_ID=<access-key>`<br>`export AWS_SECRET_ACCESS_KEY=<secret-access-key>`|
+| **Linux** | `export AWS_ACCESS_KEY_ID=<access-key>`<br>`export AWS_SECRET_ACCESS_KEY=<secret-access-key>`|
+| **macOS** | `export AWS_ACCESS_KEY_ID=<access-key>`<br>`export AWS_SECRET_ACCESS_KEY=<secret-access-key>`<br>|
+
+These credentials are used to generate pre-signed URLs that are used to copy objects.
 
 ## Copy objects, directories, and buckets